Due to the explosive increase in the number of Internet users and various new services, traffic volume is increasing dramatically every year. This trend will likely continue since novel network applications like VoIP and Video on Demand are emerging. These types of services are difficult to realize on the existing best effort type IP network. Accordingly, enterprise users, which employ various network applications, utilize more dedicated network services like IP-VPN and Ethernet as well as the leased-line service. This suggests the need for an adaptive network control mechanism that offers various transmission speeds and levels of communication quality to support user demands and new applications in the next generation networks. MultiProtocol Label Switching (“MPLS”) and Generalized MPLS (“GMPLS”) technologies are the key contenders to achieve this adaptive network control mechanism. MPLS realizes traffic control in the IP network. Using the circuit switching concept seen in the telephone network, it establishes and handles traffic flows that satisfy different service quality demands. At present, MPLS technology is being used to realize traffic management in Internet service providers and to realize IP-VPN services. GMPLS is a new control technology designed for the next-generation photonic networks. GMPLS extends MPLS to encompass time-division (for example, SONET ADMs), wavelength (that is, optical lambdas), and spatial switching (for example, incoming port or fiber to outgoing port or fiber). GMPLS represents a natural extension of MPLS to allow MPLS to be used as the control mechanism for configuring not only packet-based paths, but also paths in non-packet based devices such as optical switches, TDM muxes, and SONET ADMs. GMPLS enables unified control management of the network layers (packet/TDM/wavelength/optical fiber). The use of GMPLS unifies network operations which promises to yield significant network operation cost reductions. The GMPLS architecture is designed to permit a router to act as an edge device, that is, a Generalized Label Edge Router (“GLER”), into a lambda, fiber, or TDM switched core of Generalized Label Switch Routers (“GLSRs”). For a GLER to initiate paths, the GLER must be able to compute a viable path through the core and subsequently signal the path via GMPLS Signaling Resource ReserVation Protocol—Traffic Engineering (“RSVP-TE”) with a high degree of probability that the path will be viable. In other words, the edge routers must have a reasonable view of the topology to request a path in the first place.
The present invention addresses this, and other issues, by providing virtual routers for GMPLS networks that abstract photonic sub-domains. A virtual router uses a link viability matrix to keep track of the set of viable connections between inputs and outputs of a photonic sub-domain. A virtual router may receive RSVP-TE signaling messages and either allocate a working input to output link pair or, if explicitly signaled, verify that the requested link is currently viable. A virtual router also advertises, in its link state updates, the current set of possible outputs for any input link. Shortest path computations can be implemented utilizing virtual routers by modifying a topology graph in accordance with the link viability matrix of the virtual router.